Knuckles the Echidna: Successfully complete all Town Stage missions with an "S" rank.

Miles "Tails" Prower: Successfully complete all Town Stage missions.

Rouge the Bat: Successfully complete all GUN Commander missions.

Audio Room music

Successfully complete the indicated episode with a 100% rank to unlock the corresponding theme in the Audio Room:

Elise's Theme: The Last Episode

Shadow's Theme (All Hail Shadow): Shadow's Episode

Silver's Theme (Dreams of An Absolution): Silver's Episode

Sonic's Theme (His World): Sonic's Episode

Very fast Sonic

In Multiplayer mode in any level or match, equip the Red Gem on Sonic, activate it and hold it, then die. While still holding the activation button, wait until you respawn. When you respawn, deactivate the gem. You will now run much faster than normal and the time will automatically be slow.

Longer jumps with Silver

Jump with Silver by pressing A, then press A again while in mid-air. This makes Silver float around. When floating in mid-air, tap A while moving in any direction instead of holding the button down to make Silver jump further.

Infinite jump

There is a glitch in the purple gem you can purchase at the market. The purple gem allows you to "change size" in the description, shrinking you down to fit in small areas. However, when using the gem for Sonic you can jump an unlimited amount of times. When you press Jump while holding Activate Gem and repeatedly tap A, your character will act as if he wants to do the homing attack. However, the game will glitch, cancel it out, and allow you to jump as many times as desired while moving in the direction you wish to go. This allows you to get to interesting parts of Soleena or an action stage that you were not meant to access. If you die or find a alternate way to lose the gem, it may be "out of stock" for some time.

Mini Sonic

Select Multiplayer mode and choose Battle mode. Select Sonic and Silver and go to any level. Get to the first checkpoint and have Sonic fall and appear at the checkpoint; however, do not move him. Then, make Silver fall and appear at the checkpoint. Just when Silver appears, freeze Sonic (RT). When he is frozen he appears very small.

Select Sliver from the episode selection menu. Note: This works better if you have completed Sliver's episode. Walk to the part of the pier from where as Tails or Sonic you travel to Wave Ocean. Next to the building should be a barrel with no cover. If desired, go inside. This makes it easier to get Blaze in. After a few attempts of spinning in circles, Blaze should come in. If you are near the edge of the barrel, use Psychokinesis and you should see Silver's head pop out of the barrel. If you have a lot of patience, you can get Blaze to be in the barrel and Sliver on top after fooling around with it.

Sideways jump

Select Sonic from the episode selection menu. Note: This works better if you have completed Sonic's episode. Go to the building that is part of the Desert Stage (not the place where the Transportation Mirror is located). On the opposite side of the mirror, there should be a wall. Use the "Sliding" technique to get under the wall. While Sonic is landing on the roof, Sonic should do a sideways spin instead of a normal one. Note: This may not work every time.

Go outside boundaries when fighting Silver

Play as Sonic in Story or Trial mode. Select the Silver Boss battle and get as many rings as possible (fifteen). Then, go to the alley in the corner. Try to get as far into the corner as possible. When Silver uses his levitation technique, try to get back in the corner. Silver will try to use the levitation technique again. The rings will be behind you. When you hit the wall, try to collect your rings. You should then go outside the level's boundary. You will be able to walk on invisible bridges and hit other invisible things. Silver might also get out of the level boundary and throw you out of Soleona and you will keep flying forever.

Defeating big enemies faster

When facing an enemy that requires more than one hit, use your Homing Attack on it then use your Bounce Attack. Note: You must first have the Bounce Bracelet.

Defeating Silver

When you fight Silver with Sonic, first do a slide move into him as he is falling from the sky. Then, collect a ring and run around until you hear "How bout this?", then do a homing attack on him. Run away again until you hear "How bout this?" again. then do a homing attack again. Repeat this until he is defeated.

Defeating Solaris

First, use Silver to weaken him until his first arm guard falls off. Then, switch to Shadow and hit him with the beams until his second arm guard falls off. Next, use Sonic to defeat the rest of his first form. Finally, use all three to survive the blows of lasers, and continuously attack.

Achievements

Accomplish the indicated achievement to get the corresponding number of Gamerscore points: